Prozac and Effexor should not be taken together as the combination can increase the Effexor levels in your body. Furthermore, the combination can also increase the risk of cardiac arrhythmias. Finally the combination can increase the levels of serotonin in your body and lead to a dangerous reaction called serotonin syndrome. In terms of adverse reactions, Prozac is not known to cause hot flashes as such the reaction that you are having may be idiosyncratic. I suggest that if you do not like the feel that Effexor gives you and the hot flashes that Prozac gives you, then you can consider taking Lexapro.
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